package main

import "fmt"

var num, letter = make(chan bool), make(chan bool)

func printNum() {

	i := 1
	for {
		<-num
		fmt.Printf("%d%d", i, i+1)
		i += 2
		letter <- true
	}
}

func printLetter() {

	str := "ABCDEFGHIJKLMNOPQRSTUVWXYZ"
	i := 0
	for {
		<-letter
		if i >= len(str) {
			return
		}
		fmt.Printf("%c%c", str[i], str[i+1])
		i += 2
		num <- true
	}
}
